pgsql: Treat any negative ws_file as closed in xlogreader.c

Treat any negative ws_file as closed in xlogreader.c

The segment_close() callback is required to set ws_file to a negative
value after closing a WAL segment, as documented in xlogreader.h.
XLogReaderFree() only treated -1 as closed, so it could call
segment_close() again if another negative value was used.

This should not be an issue in practice, but all the other code paths in
the tree use 0 as comparison base when dealing with ws_file, except for
the line updated here. Let's be consistent, at least.

Author: Bertrand Drouvot <bertranddrouvot(dot)pg(at)gmail(dot)com>
Discussion: https://postgr.es/m/asNr203eue0R4zpZ@bdtpg

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/412848dac37f2e4455e1505f83f0af0f3d28a67d

Modified Files
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src/backend/access/transam/xlogreader.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)